On Mon, 1 Feb 2016 12:47:51 +0100
Didier Kryn <kryn@???> wrote:

>      Apparently synaptic keeps its config in its own config file 
> /etc/apt/apt.conf.d/99synaptic. Do you mean synaptic reads all config 
> files in order, and since 99synaptic is the last, it can override all 
> previous settings? 

For the fun of it, I just ran an "apt-get install --install-recommends
--no-install-recommends" and it chose to not install the recommends.
The same with contradicting lines in apt.conf(.d/*):

APT::Install-Recommends "0";
APT::Install-Recommends "1";

This will install the recommends, the other way around it won't.
Apparently there's still some behavior left in modern Linux that is
coherent with an autistic mindset, hahaha.

> I must confess I don't understand how this set of
> config files is processed; there are quite a lot of files in
> etc/apt/apt.conf.d/. There's a man for apt.conf, which doesn't exist
> and no man for apt.conf.d, which exists!

As with any of these newish "*.d/" folders, you can just

$ cat apt.conf.d/* > apt.conf && rm -r apt.conf.d/

without any consequences regarding the configuration. AFAIU this is all
about easier deployment (and automated removal) of configurations - like
hitting some button on a shady website to add distribution independent
repositories to the sources.list.

Regards,

Florian